Don´t mix up things here is my advice. See, the PL/SQL language was built to read record, process cursors, make calcs and related tasks - it DO NOT have any command to interact with users, make screens/display itens, and the like. So, you need use the resources from the environment where your PL/SQl is running. If you r using sql*plus, it implies in using the only commands to interaction with users : ACCEPT, PROMPT and running text-scripts with @ / START / @@.
Similarly, the SQL language only copes with data-manipulation (INSERTs, UPDATEs, SELECTs, etc) = YOU CAN NOT MIX FREELY ONE LANGUAGE WITH ANOTHER, there are restrictions.

With this info in mind, to resolve your problems :

a) read the SQL*PLUS user´s guide and the sql*plus reference manuals, to know the possibilities and get some examples

b) check the sql*plus FAQ in [url]http://www.orafaq.com/faq.htm[/url]

c) AFTER a) and b), get an advanced sql*plus book , I liked "Oracle SQL*Plus, The Definitive Guide", by Jonathan Gennick, O'Reilly & Associates, 1999.

WIth all this info, you will be able to alter your scripts successfully.

OBS : another option can be run PL/SQL in a more sofisticated environment, like Oracle Forms - this way, you will be able to get user input, let the user interact with your PL/SQL code with mouse/GUI, etc.

Regards,

Chiappa